window.onload = function() {
    let username = document.getElementById("username")
    console.log(username.value)
    
    let sexMale=document.getElementById("male")
    console.log(sexMale.checked)
    sexMale.checked=true
    sexMale.addEventListener("change",(e)=>{
        console.log("复选框有变化")  
        console.log(sexMale.checked)  
    }
)
}